public function testHopeRemovingTargetDoesNotChangeMuchWithCrc32Hasher()
{
$hashSpace = new Flexihash(new Flexihash_Crc32Hasher());
foreach (range(1, $this->_targets) as $i) {
$hashSpace->addTarget("target{$i}");
}
$results1 = array();
foreach (range(1, $this->_lookups) as $i) {
$results1[$i] = $hashSpace->lookup("t{$i}");
}
$hashSpace->removeTarget("target1");
$results2 = array();
foreach (range(1, $this->_lookups) as $i) {
$results2[$i] = $hashSpace->lookup("t{$i}");
}
$differences = 0;
foreach (range(1, $this->_lookups) as $i) {
if ($results1[$i] !== $results2[$i]) {
$differences++;
}
}
$percent = round($differences / $this->_lookups * 100);
$this->dump("ConsistentHash: {$percent}% of lookups changed " . "after removing 1 of {$this->_targets} targets");
}
public function testFallbackPrecedenceWhenServerRemoved()
{
$mockHasher = new MockHasher();
$hashSpace = new Flexihash($mockHasher, 1);
$mockHasher->setHashValue(10);
$hashSpace->addTarget("t1");
$mockHasher->setHashValue(20);
$hashSpace->addTarget("t2");
$mockHasher->setHashValue(30);
$hashSpace->addTarget("t3");
$mockHasher->setHashValue(15);
$this->assertEqual($hashSpace->lookup('resource'), 't2');
$this->assertEqual($hashSpace->lookupList('resource', 3), array('t2', 't3', 't1'));
$hashSpace->removeTarget('t2');
$this->assertEqual($hashSpace->lookup('resource'), 't3');
$this->assertEqual($hashSpace->lookupList('resource', 3), array('t3', 't1'));
$hashSpace->removeTarget('t3');
$this->assertEqual($hashSpace->lookup('resource'), 't1');
$this->assertEqual($hashSpace->lookupList('resource', 3), array('t1'));
}
